Effect of Patient Weight and Anesthetic Technique on CO2 Excretion During Thoracoscopy in Children Assessed by End-Tidal CO2

Abstract

The aim of this study was to review the changes in CO(2) excretion and anesthetic management during thoracoscopy in children. We analyzed end-tidal carbon dioxide concentration (EtCO(2); kPa) during CO(2) pneumothorax. EtCO(2) was measured on a continuous basis by using a positive sampling system and recorded every 10 minutes. Baseline and highest EtCO(2) were used to derive the maximum change in the intraoperative period. EtCO(2) was also analyzed in three time periods: (1) preinsufflation, (2) during insufflation of CO(2) into the chest, and (3) after desufflation. Core temperature was also recorded as an index of thermoregulation. Data are presented as the mean +/- standard error of the mean. Differences within time periods were compared by using paired t tests or repeated measures analysis of variance. Correlation between changes in EtCO(2) and patient demographics was performed by using linear regression. The pattern of change was compared to children undergoing laparoscopy. Median age was 1.9 years (range, 1 day to 15 years). EtCO(2) increased significantly from preinsufflation 5.1 +/- 0.2 to 6.4 +/- 0.3 during insufflation (P < 0.01); values were still significantly elevated after desufflation 6.4 +/- 0.4 (P < 0.01). Single-lung ventilation was associated with higher EtCO(2) levels during insufflation than with two-lung ventilation (P = 0.02). Maximum change in the EtCO(2) in the group undergoing one-lung ventilation negatively correlated to patient weight (r(2) = 0.25, P = 0.02); this correlation was not present with two-lung ventilation (r(2) = 0.02, P = 0.84). Laparoscopy increased EtCO(2) from 4.7 +/- 0.2 preinsufflation to 5.3 +/- 0.2 (P < 0.001) during and decreased to 4.8 +/- 0.2 postdesufflation (P = 0.60). There was a significant increase in core temperature from 35.9 +/- 0.3 to 36.9 +/- 0.2 postoperatively (P = 0.007). There is a significant increase in EtCO(2) in children undergoing thoracoscopy, which is higher than during laparoscopy. Changes in EtCO(2) are larger in smaller children undergoing single-lung ventilation. Thoracoscopy may preserve intraoperative thermoregulation.